Micro stages having high precision and rapid responding ability are of great importance in modern manufacture technology and reflect the high-tech level of technical development of a country. In a super-precise machine tool, a super-precise micro stage is used for compensating the error of a feeding system, for achieving super-precise processing. In large scale integrated circuit manufacturing, super-precise micro stages are used in lithographic equipments for achieving micro positioning and micro feeding. In scanning microscopes, super-precise micro stages are used for detecting sample surface profile and nano processing. In biotechnology, super-precise micro stages are used in cell treatments, for achieving industrialized bio treatments. In medical field, super-precise micro stages are used in micro surgeries for alleviating operation labor, shortening operation time and increasing success rate. In addition, super-precise micro stages are also generally used in optical fiber joining, in processing, packaging and assembling of MEMS, in chemical-electrical processing, and the like.
In semiconductor lithographic equipment, it is known that a lithographic machine comprises a wafer table and a mask table each generally comprising a stacked structure of rough-precise stages, in which a super-precise micro stage is superimposed on a rough stage for compensating the precision of the rough stage. The exposure precision of the lithographic machine is mainly determined by the positioning precision of the micro stage, and the production efficiency of the lithographic machine is mainly determined by its movement velocity. Thus, super-precise micro stage technique is regarded as a key factor of lithographic machines in the United States, Japan, European and other developed countries, while China is facing severe restriction to importation of correlated products.
For summarization of current study on nano-level micro stages in China, three types of super-precise micro stage are generally mentioned, i.e., micro stages driven by servo motors via screws and supported by linear guides, micro stages driven by piezo ceramics and supported and guided by flexible hinges, and micro stages driven by voice coil motors or variable reluctance motors and supported by air-floating or magnetic floating means.
The former two types of micro stages, under the negative influence of non-linearity of frictional damping of their supporting systems and other factors, cannot meet the requirements of high velocity, high load and high dynamic performance of lithographic equipments. Micro stages, driven by voice coil motors and supported by air-floating means, although meet the requirements of lithographic equipments, suffer from poor structural integrity, bulky stage body, high weight center, etc., which result in various limitations to their performances.
The same applicant of the invention filed a Chinese patent application No. 200610169826.6, titled by “Ultra Thin Planar Motor with 3 Degrees of Freedom”, on Dec. 29, 2006 and a Chinese patent application No. 200710098790.1, titled by “Ultra Thin Micro Stage with 3 Degrees of Freedom”, on Apr. 27, 2007. The former application discloses an ultra thin structure of a single layer of coil, for avoiding various problems, such as poor structural integrity, found in prior art in which three degrees of freedom are achieved by multiple linear motors, while the later application discloses a 3 degree-of-freedom micro stage for a mask table of a lithographic machine, which uses air floating or magnetic floating bearings. On the basis of the above two applications, the present invention is aimed at providing a 6 degree-of-freedom micro stage which can be used in a wafer table of a lithographic machine, which micro stage is able to compensate the positioning error of the wafer table of the lithographic machine and to achieve the leveling and focusing of the lithographic machine.